Hey guys. This circuit will work correct? I'm hooking everything up right now and then will solder everything together. Just wanted to know if you guys see any problems with the final output at the USB being 5v.



EDIT: By the way! The LM78XX is a LM7805 which is a 5v voltage regulator.
Can you specify which LM78XX that is, exactly?
It is a LM7805C; 5v Regulator.
joshie75 wrote:
It is a LM7805C; 5v Regulator.
And here's the datasheet for that part:

http://www.ti.com/lit/ds/symlink/lm340-n.pdf

They specify a 0.22uF capacitor on the input side; why did you choose to go with 0.33uF instead? It doesn't really matter, since your source is a 9V battery and thus should have almost no fluctuation at all to smooth out, though.
I was looking at another data sheet and I saw the .33uF. I actually grabbed part of that picture up there from that datasheet.
joshie75 wrote:
I was looking at another data sheet and I saw the .33uF. I actually grabbed part of that picture up there from that datasheet.
It should be fine; don't worry about it. Just make sure you stick a multimeter across the output and look at what the regulator is giving you before you plug in anything valuable, to make sure that you won't suddenly find yourself with 9V flowing into your delicate electronics.
Thanks Kerm. Will be sure to do so! Smile
joshie75 wrote:
Thanks Kerm. Will be sure to do so! Smile
And of course let us know how it goes. Smile Are you doing a twist-and-tape build, twist-solder-tape, or real perfboarding?
Sorry for the uber late reply Kerm, It is in-fact a combination of your first two, I'm doing the twist, solder, tape method Very Happy

So I FINALLY got my hands a on a digital multimeter. I've been trying to hunt one down at school since I remember using them last year but no luck so I finally went out tonight and just bought one.

EDIT: I made a nooby mistake, I was shaking the leads from the multimeter a little bit, causing the volt reading to fluctuate. I taped the leads in place and got a clean output, no fluctuation.

I have my circuit set up EXACTLY as above. I tested the output voltage and got an output voltage of 5.02v. My phone charges at 5v at a current of .7 amps. Yet when I plug my phone into this contraption, my phone is not charging. HELP! Sad
A variety of possible reasons, but it's nothing to be worried about. In most circuits, you're okay as long as voltages are within 10% of the target.
Could be your multimeter, could be thermal effects, could be effects from you holding the meter. That's not to worry about too much, especially since it's fluctuating further down than up, in my opinion.
I tested the output voltage and got 5.02v. My phone charges at 5v at a current of .7 amps. Yet when I plug my phone into this contraption, my phone is not charging.

I tested the outputs of USB ports where my phone is correctly charging, here are my findings;

Laptop USB=5.14v
Manufacturer charger (plugs into wall)=5.20v
Computer USB=4.99v

There should be no reason why my phone won't charge at 5.02 Sad
joshie75 wrote:
I have my circuit set up EXACTLY as above. I tested the output voltage and got an output voltage of 5.02v. My phone charges at 5v at a current of .7 amps. Yet when I plug my phone into this contraption, my phone is not charging. HELP! Sad

It's not uncommon for 'smart' devices to key to some sort of communication in order to begin charging. In this case, I might guess that your phone is unable to negotiate any link parameters (since there's no USB host), so simply does nothing.

USB limits maximum draw from any device to 100 mA before enumeration, and enumerated devices can negotiate for up to 1.5A (depending on the host's capabilities). Wikipedia notes that the data lines on a dedicated charging port are usually tied together, so you may want to try that. If that doesn't work, you may be able to get a similar effect with a voltage divider on the data lines to indicated to the device how much current it can draw from that dumb port, but that's more hacky.
Solved!! Apologizing for my stupidity right now :p The female USB had a guarding around it, and my phone charger MALE USB has a bit larger cover than normal; so when I plugged the male into the female, while it looked like it was plugged in, it actually wasn't. I used some needle nose pliers to open up the female USB protector a little bit and they fit together perfectly and my phone is charging. Thanks for the help guys and sorry for the hassle Smile
Woot, glad that it's working now! If I were to make any suggestions, it would be to take your electronics knowledge a bit further by perfboarding this or even designing a simple custom PCB.
That doesn't sound like a bad idea Kerm. Now I know how to breadboard. The horizontal set of holes are all connected. Perfboards though, I've never worked with. Are any of the holes connected to each other, or do you solder a wire in with the component to connect it to another?
joshie75 wrote:
That doesn't sound like a bad idea Kerm. Now I know how to breadboard. The horizontal set of holes are all connected. Perfboards though, I've never worked with. Are any of the holes connected to each other, or do you solder a wire in with the component to connect it to another?
There's stripboard, which is like a soldering version of a breadboard, where you need to slice the long rows of connected holes to make smaller sets of connected holes. There's also plain perfboard where you need to run wires (or make solder bridges).
  
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